In this study,the corrosion behavior of the CuAl-NiC abradable seal coating system in chloride solution was investigated to systematically research the effect of porosity,multiphase,and multilayer structure on the cor...In this study,the corrosion behavior of the CuAl-NiC abradable seal coating system in chloride solution was investigated to systematically research the effect of porosity,multiphase,and multilayer structure on the corrosion failure.Through the composition and structure analysis,the corrosion process of the system was predicted and then verified with mercury intrusion porosimetry,cross-section SEM/EDS analysis,and electrochemical measurements.The results demonstrated that the interphase selective corrosion caused the porosity of the top layer to decrease first and then increase during the corrosion development.The interlayer galvanic corrosion,determined by the pore connectivity,is crucial for corrosion failure.展开更多
As promising abradable seal coating materials used in high temperature range, the homologous layered InFeO3（ZnO）m （m = 1, 2, 3...20） have attracted great attention. In this short review, we summary the research pr...As promising abradable seal coating materials used in high temperature range, the homologous layered InFeO3（ZnO）m （m = 1, 2, 3...20） have attracted great attention. In this short review, we summary the research progress in InFeO3（ZnO）m that were developed in our group. We first introduced a series of conventional abradable seal coating materials as a research motivation. Second, the phase composition and crystal structures of lnFeO3（ZnO）m system were presented. Then, their thermophysical properties, as the most important part, were introduced in detail. At last, the mechanical properties such as hardness, friction coefficient, erosion wear resistance of InFeO3（ZnO）m system were also described. Our summary indicates that InFeO3（ZnO）m sys- tems are promising abradable seal coating materials.展开更多
Modern aero and stationary gas turbine engines have been designed with much higher compressor-pressure ratios and thrust-weight ratios than earlier models,and these ratios are strongly influenced by the hot-running cl...Modern aero and stationary gas turbine engines have been designed with much higher compressor-pressure ratios and thrust-weight ratios than earlier models,and these ratios are strongly influenced by the hot-running clearances between the rotating and stationary components.The main benefit of reduction in the clearances is efficiency gains,resulting in lowered fuel consumption and polluting gas emissions,with ecological and economic advantages.However,at these undersized clearances,some rubbing interactions are unavoidable,which can be accommodated by applying Abradable Sealing Coatings(ASCs)on the stationary inner surface.This paper reviews the commercially available abradable materials for thermal spraying at various application positions and temperatures.Emphasis is placed on the abradability and wear mechanisms involved.In addition,considering the tendency of SiC/SiC ceramic matrix composites replacing superalloys as hot section components,the future prospect of ceramic abradables based on Environmental Barrier Coatings(EBCs)in turbine stages is summarized and a new concept of"self-degradable ceramics"based on the corrosive steam environment is proposed for the purpose of high-temperature fillerfree abradables.展开更多
To solve the long-standing contradiction between the bonding strength and abradability of an abradable seal coating(ASC),a novel spherical closed-pore structure was proposed.The new structure consisted of three discon...To solve the long-standing contradiction between the bonding strength and abradability of an abradable seal coating(ASC),a novel spherical closed-pore structure was proposed.The new structure consisted of three discontinuous phases,including locally enriched metals,hollow thin-shell spheres,and pores.The results show that the bonding strength of the abradable seal coating reaches 25.4 MPa,and the abrasion ratio between the coating and blade tip,as a characteristic of the abradability of ASCs,is>5900.The dewetting kinetics of the metal film on the ceramic sphere were calculated.The size of the shrink metal hemisphere is 3.6 times the metal film thickness.The locally enriched metal enables a high bonding strength,while the fragmentation of the hollow thin-shell spheres enhances the abradability,thus simultaneously improving the strength and abradability.The coating is expected to be used in next-generation turbines to improve efficiency and stability.展开更多
In aero-engines, abrasive coatings are typically utilized to protect the blade tip from excessive wear caused by the harder abradable sealing coating and thereby improve the sealing performance of engines. Therefore, ...In aero-engines, abrasive coatings are typically utilized to protect the blade tip from excessive wear caused by the harder abradable sealing coating and thereby improve the sealing performance of engines. Therefore, a Ni/cBN abrasive coating was prepared on titanium alloy using electrodeposition. The high-speed rubbing tests with a linear velocity of 350 m/s and different incursion rates were performed to investigate the effect of the Ni/cBN abrasive coating on the wear behavior against NiCrAl/diatomite seal coating. Results showed that melting wear and adhesive transfer occurred on the bare blades, causing the bare blade to suffer excessive wear. While the Ni/cBN abrasive coating exhibited superior wear resistance and cutting performance. The cBN grits pullout, the abrasion of Ni matrix and transfer of seal coating to the cBN grits were the main wear mechanism of the Ni/cBN abrasive coating. Additionally, it was found that the relationship between the incursion rate and high-speed rubbing behavior is quite different for the bare blade and Ni/cBN coating. The reason for the difference in wear behavior of bare blade and Ni/cBN coating at different incursion rates was discussed in detail.展开更多
Reliable service of indispensable titanium alloys in aeroengines is limited by the bottleneck problem of titanium fires.In this study,a tri-layer fire retardant coating with a bi-functional ceramic barrier layer is pr...Reliable service of indispensable titanium alloys in aeroengines is limited by the bottleneck problem of titanium fires.In this study,a tri-layer fire retardant coating with a bi-functional ceramic barrier layer is proposed to suppress titanium fire.Results show that the current coating can increase the fire retardant temperature by≥300 K under droplet ignition.Thermal barrier effect of the YSZ refractory ceramic layer significantly reduces Ti alloy temperature,and oxygen barrier effect prevents active Ti from directly contacting oxygen during the entire ablation process.Therefore,the two barrier effects effectively prevent occurrence of titanium fire.In addition,dissolution of the Ni-based abradable seal coating makes burning TC4 molten droplet extinguished in a short time,thus further inhibiting titanium fire ignition.The present study provides an effective method for reliable service and titanium fire-resistant design of titanium alloys.展开更多
基金financially supported by the National Natural Science Foundation of China(No.51671198)。
文摘In this study,the corrosion behavior of the CuAl-NiC abradable seal coating system in chloride solution was investigated to systematically research the effect of porosity,multiphase,and multilayer structure on the corrosion failure.Through the composition and structure analysis,the corrosion process of the system was predicted and then verified with mercury intrusion porosimetry,cross-section SEM/EDS analysis,and electrochemical measurements.The results demonstrated that the interphase selective corrosion caused the porosity of the top layer to decrease first and then increase during the corrosion development.The interlayer galvanic corrosion,determined by the pore connectivity,is crucial for corrosion failure.
基金financially supported by the National Natural Science Foundation of China(Nos.51671015,51571007 and 51772012)the Beijing Municipal Science and Technology Commission(No.Z171100002017002)the Shenzhen Peacock Plan team(No.KQTD2016022619565911)
文摘As promising abradable seal coating materials used in high temperature range, the homologous layered InFeO3（ZnO）m （m = 1, 2, 3...20） have attracted great attention. In this short review, we summary the research progress in InFeO3（ZnO）m that were developed in our group. We first introduced a series of conventional abradable seal coating materials as a research motivation. Second, the phase composition and crystal structures of lnFeO3（ZnO）m system were presented. Then, their thermophysical properties, as the most important part, were introduced in detail. At last, the mechanical properties such as hardness, friction coefficient, erosion wear resistance of InFeO3（ZnO）m system were also described. Our summary indicates that InFeO3（ZnO）m sys- tems are promising abradable seal coating materials.
基金Supported by the National Natural Science Foundation of China(Nos.U2241238,52275461,and 92060201)the Major Program(JD)of Hubei Province,China(No.2023BAA003)the Key Research and Development Program of Hubei Province,China(No.2023BAB107).
文摘Modern aero and stationary gas turbine engines have been designed with much higher compressor-pressure ratios and thrust-weight ratios than earlier models,and these ratios are strongly influenced by the hot-running clearances between the rotating and stationary components.The main benefit of reduction in the clearances is efficiency gains,resulting in lowered fuel consumption and polluting gas emissions,with ecological and economic advantages.However,at these undersized clearances,some rubbing interactions are unavoidable,which can be accommodated by applying Abradable Sealing Coatings(ASCs)on the stationary inner surface.This paper reviews the commercially available abradable materials for thermal spraying at various application positions and temperatures.Emphasis is placed on the abradability and wear mechanisms involved.In addition,considering the tendency of SiC/SiC ceramic matrix composites replacing superalloys as hot section components,the future prospect of ceramic abradables based on Environmental Barrier Coatings(EBCs)in turbine stages is summarized and a new concept of"self-degradable ceramics"based on the corrosive steam environment is proposed for the purpose of high-temperature fillerfree abradables.
基金financially supported by the National Sci-ence and Technology Major Project(No.2017-VII-0012-0107)the Postdoctoral Innovative Talent Support Program(No.BX2021238)the National Natural Science Foundation of China(No.U22A20110).
文摘To solve the long-standing contradiction between the bonding strength and abradability of an abradable seal coating(ASC),a novel spherical closed-pore structure was proposed.The new structure consisted of three discontinuous phases,including locally enriched metals,hollow thin-shell spheres,and pores.The results show that the bonding strength of the abradable seal coating reaches 25.4 MPa,and the abrasion ratio between the coating and blade tip,as a characteristic of the abradability of ASCs,is>5900.The dewetting kinetics of the metal film on the ceramic sphere were calculated.The size of the shrink metal hemisphere is 3.6 times the metal film thickness.The locally enriched metal enables a high bonding strength,while the fragmentation of the hollow thin-shell spheres enhances the abradability,thus simultaneously improving the strength and abradability.The coating is expected to be used in next-generation turbines to improve efficiency and stability.
基金supported by the National Science and Technology Major Project(2017-VII-0012-0108).
文摘In aero-engines, abrasive coatings are typically utilized to protect the blade tip from excessive wear caused by the harder abradable sealing coating and thereby improve the sealing performance of engines. Therefore, a Ni/cBN abrasive coating was prepared on titanium alloy using electrodeposition. The high-speed rubbing tests with a linear velocity of 350 m/s and different incursion rates were performed to investigate the effect of the Ni/cBN abrasive coating on the wear behavior against NiCrAl/diatomite seal coating. Results showed that melting wear and adhesive transfer occurred on the bare blades, causing the bare blade to suffer excessive wear. While the Ni/cBN abrasive coating exhibited superior wear resistance and cutting performance. The cBN grits pullout, the abrasion of Ni matrix and transfer of seal coating to the cBN grits were the main wear mechanism of the Ni/cBN abrasive coating. Additionally, it was found that the relationship between the incursion rate and high-speed rubbing behavior is quite different for the bare blade and Ni/cBN coating. The reason for the difference in wear behavior of bare blade and Ni/cBN coating at different incursion rates was discussed in detail.
基金financially supported by the National Science and Technology Major Project(No.2017-VII-0012-0107)
文摘Reliable service of indispensable titanium alloys in aeroengines is limited by the bottleneck problem of titanium fires.In this study,a tri-layer fire retardant coating with a bi-functional ceramic barrier layer is proposed to suppress titanium fire.Results show that the current coating can increase the fire retardant temperature by≥300 K under droplet ignition.Thermal barrier effect of the YSZ refractory ceramic layer significantly reduces Ti alloy temperature,and oxygen barrier effect prevents active Ti from directly contacting oxygen during the entire ablation process.Therefore,the two barrier effects effectively prevent occurrence of titanium fire.In addition,dissolution of the Ni-based abradable seal coating makes burning TC4 molten droplet extinguished in a short time,thus further inhibiting titanium fire ignition.The present study provides an effective method for reliable service and titanium fire-resistant design of titanium alloys.
